Fluid pressure control apparatus for free piston machines



Dec. 1, 1953 I A. J. BENT 20 FLUID PRESSURE CONTROL APPARATUS FOR FREEPISTON MACHINES Original Filed Jilly 22, 1947 IN VEN TOR.

By Arihur JBent ATTORNEY piston is what ma Patented Dec. I, 1953 PRESSURE CONTR L APPARATUS i-EORQFREEPISTON MACHINES -'-Ai thur 3i. Ben't,Tenn Township, Allegheny 'Gou'nty, Pa., assignor 1:0 Westinghouse AirBrakesGompainy, arcorporation of :Pennsylvania b f-iginal "application-July 22, 1947, Serial .No. ."H1"2;,"7"Z1 ,"now Patent No. "2,608,052,dated August 26, 1952. V "Divided and this application il'un'e 15, 1948,Se'lial N 0. 33,044

.lI hisI'inventiomrelatese toscontrolzapparatuszfor jfreepiston machines;;particularly: of: thezgasggen- .erator type, embodying ;two:oppos'itelyiarranged motorzoperated'fair: compressor portionseachembodying an 7 internal tcdr nbustion :ope'rated ;power.pistonrandacoaxial-lyarran'ged anti rigidly Iconnested air "compresscr:piston 'iiperative by "said powerz'piston T t0 compress airiforscavenging and 'feed of the motoripart of the machine and in which the=miizture'fofthe ilidt gase's ofscdmbustion and "of the excess of.vgcavenger'air discharged from ttheiimotor I'pait "of the machine form:together i'generated :motive gas which may' be employedto performmechanical worktasby expansion. in a"turbin'e,;the:present applicationbein'g a division of "my :coiaending application serial No. 762177 1,:filed Jilly 22, $19.47, .fnow Patent No. 2,608,052,issuedAligustfi6;fl952.

vIn Patent 3N0. 12,406,037 1 issued dn 'August 20, 1946, to R. P. Ramseythere is disclosed a free piston: machine iof *this igeneral type whichembodies "two ioppositely a d coaxially arranged motorcompressor-cunitseach emlcodying-af piston assembly comprising a powerpistonmn air 'com- "pressor'piston'and a direct' bounce piston. Be-

tween the two power pistons is a power or combustiOnYchamber intD whichfu'el is adapted t'o be injected for compressionignition-Tor-driving's'a-id pistons apart. th'e oiiter face of e'achaircompressoripistoniis an air ompressingchamber and said piston isoperative by the respective-power piston zto compress *a'i'r i'r oin-said chan'1b'er into a scavenger "receiver 1 fd'r -the urpose *ajboveset forth. :At l thef out'er frace of=-each direct bounce e called -?adirect bounce chamberZ iHWhich-ai adaptedto becomipressed upcn theai'ricoih" re'ss'iiig stranger *therespetive power piston "nergyfor'turning the toits inner position "preceding mother mowerst oke.

"amount cif air necessary in the direct fl'aounce fuel supply to thecombustion chanib'erfmust-be vention.

:bounceigovernor idevice controlled :by' pressureeof air inithescavenger receiver-and the-stroke ofrthe piston assembliesforautomaticall-yso regulating the amount of air inthedireetbouncechambers.

Other objectsvand advantages'will appearirom the following moredetaileddescriptionpf the in- In the accompanying drawing "the'singlevfigur'e is a diagrammatic,-:sectional"view of adirectfbounce'igovernor -='dev-ice embodying the invention.

.-DES.CRIPTION As shown in the drawing, :thedirect .bounce governordevice comprises ia"fluid-;pressure regulating mechanism "359:150-1'controlling the "pressure of-fiuid in thedirect"bouncechambersof a freepiston gas'generatorKnot-shown) and"a:control portion 3 5 [for"controlling operation "of said regulating mechanismsaid mechanism andcontrol portion'comprising acommon casingrse'ction 352 mounted on apipebracket"353 'and'the said mechanismcomprising in addition a .casing sec-'tion 354a mounted'on the casing section 352.

"The fluid pressure regulating mechanism 350 comprises a supply valve355 contained in 4a 'chamber '6and"arranged to cooperate with a seat'3'57for controlling flowof fluidunder pressure fro'm chamber 356 to" anoutlet chamber 358 provided in bracket F353. A guide member 1359projecting above theseat. 35'! is provided 'witha tapered 'openin'gforreceiving'the valve;355 to guide it to its seat and toalso'cooperatewithisaid valve when in said opening "to throttleflow of "fluidunderpressure "from chamber 356 to the toxbeicon'stanflysupplied-viaapipe 356 with? fiuid under pressure Ffrom :@any suitable source. Theoutlet rchamberi z iifis: is Iopen'to: a 'pipe 33 0 adapted tobeconnectedi.to:'the:direct 'bounce chambers in theifreegpistoni gas"generatori lfnots'shown) iTheesupply --va-1ve :3 .i-is connectedLtOiTthGF-GHd ,of aestemz-3fi l by raj pin 362, said stem: projectingfromtapcontrol pistonr-3 63operat-ive1y mountedxin a bushing v364v held:in position-between'theicasing sections352.. and 4354a. -A-n eequalizingport 3.65 through the bushing. 354 ,iscprovided :to; per- .mitequalization of fluid pressureiromchamber 356 intolia chamber 3 E56.v at;the. stemside. of the piston 363. Atthe opposite 'side ofc.'the.pistom363 is 'a' control "chamber 36'! open 'througmarchoke 368,2;strainer 3 69 and a passage'3fi9ain thelpistonstem' 36l to chamber 356.'A'spring follower 356armountedpmthe 'stem "36 l in contact with valve1-355 is engaged by :one" end "of #a precompressed spring 368a the76111181 end or which is supported byr the' bushing'ESBMsaid springbeing Q3 provided for closing said valve upon substantial equalizationof pressure of fluid acting on opposite sides of piston 363.

Disposed in the casing section Side: is a valve seat member tlil held inplace by a retainer till secured in said casing section. The seat memberSlil has a bore open at one end to a passage 3'52 leading to the outletchamber 358 and to the control portion 35! of the direct bounce governordevice. The opposite end of this bore opens through a valve seat 373 toa chamber 314 which in turn is connected through one or more ports 315in retainer 3'75 to the control chamber 561 at the one face of piston363. Slidably mounted in a bore in the retainer 31! coaxially of thevalve seat 3 .3 is a valve 316 arranged to cooperate with seat 313 forclosing communication between chamber 3M and passage 3'l2. A plunger 31!slidably mounted in a bore in a partition wall Bit has an extension 319of smaller diameter than the axial bore in seat member 318 and extendingtherethrough for contact with the valve 3'36 for unseating it against aspring 38% carried by the retainer 315. The plunger 37'! is provided onits opposite end with a projection 3&2 extending into a chamber 3% forcooperation with a valve 383 which is slidably mounted in a bore 38%arranged in coaxial relation to said plunger Ell in an element 385secured in the casing. The valve 383 may be provided with slots 386around its edge to provide communication between opposite sides thereof.The char).- ber 382 is open through a port 387 to passage 312 andthereby to the outlet chamber 358.

A cover 3% is clamped to the end of the casing section 35% opposite thatengaging the casing portion 352, and clamped between said cover and thecasing section 35 3a is a flexible diaphrag a 3% arranged in coaxialrelation with the bore 3% in the element 385. phragm is a controlchamber 396 in which the element 385 is disposed. At the opposite sideof the diaphragm is another control chamber 3%! The chamber 396 is openthrough a passage 392 to a pipe 3% adapted to be connected directly toone of the direct bounce chambers in the gas generator (not shown), achosen restriction to flow of air through this communication beingprovided as by said pipe being of relativeh small flow capacity. Thechamber 395 is open through a choke 39 i and a passage 3&5 directly tothe fluid pressure supply pipe 354.

A diaphragm follower 3% disposed in chamber 39%! engages the adjacentface of diaphragm 389 and has a portion 39? extending through a centralopening in said diaphragm and a follower 3&5 disposed in chamber 3%!against the opposite side of the diaphragm, and these followers arerigidly clamped to opposite sides of said diaphragm by a securingelement 398 engaging the follower 398 and having internal screw-threadedengagement with the portion 39'! of the follower 396.

The diaphragm follower 396 has an integral member tilt disposed in thebore 3% in the element 385, said member 4% having a spherical likesurface in sliding contact with the wall of said bore and carrying asealing ring lili having sealing contact with said wall. On theinnermost end of the integral member 408 is formed a valve seat 492arranged for sealing engagement with the valve 333. A shoulder 403substantially en circling the valve seat tilt and projecting from thewall of bore 334 is provided for contact by valve 333 for unseating saidvalve from the mem- At one side of this diad ber 40! upon movement ofsaid member in the direction away from said valve.

The valve seat tilt encircles a fluid pressure release passage 4%extending through the integral member Mill and the follower 3% to achamber 4B5 provided at the opposite side of the diaphragm 339 in acoaxially arranged cylindrical portion 465 of the securing element 3589.Slide mounted in the cylindrical portion tilt is one of a rigid struttill the opposite end of which is slidably mounted in a bore in thecasing cover 33%, which bore is normally in coaxial relation with thecylindrical portion sec. The strut M! has an axial bore tilt!establishing communication between chamber M5 and a passage in thecasing cover 3% which passage opens to at mosphere. The opposite endportions of the strut M31 in contact with the wall of the bore in thecasing cover 3% and with the wall of the cylindrical portion @656 arerounded to permit free slight inisalignments or wobbling or thediaphragm 389 during movement thereof, which will be later described,and in each end of said strut is a sealing ring (lit having sealingslidi .v contact with the respective wall for preventi g leakage offluid under pressure from the control chamber 3%! to the atmosphericpassage M29.

The diameter of the rigid strut lm at its point of contact with thecylindrical portion ti t of the securing element 399 is greater than thediameter of the integral member see at the opposite side of thediaphragm which is disposed in the bore 334, whereby less area of thediaphragm 389 is subject to pressure oi fluid in chamber 39! than issubject to opposing pressur of fluid in chamber 396, in order that alower press of fluid in the latter chamber will provide a felt: tobalance a higher pressure of fluid in the to ac chamber duringoperation, to be hereinaf described.

The control portion tfil of the direct bou governor device comprises aflexible diaphra Ml secured around its edge between the casmsection 35land the cover H2. Between the co H2 and the diaphragm Mi is a controlchamber M3 open through a passage di t to a pipe ilt adapted to beconnected to the scavenger air receiver of the free piston generator(not shown At the opposite side of diaphragm ii 5 is a charcher M6 whichis open to atmosphere through a vent port 411.

A follower H8 disposed in chamber 55 against the adjacent face ofdiaphragm til has a portion M9 extending centrally through the diaphragminto chamber H3 and over this portion in the latter chamber is mounted afollower plate iZd against the diaphragm and a nut 42! havingscrew-threaded engagement with said stud portion for clamping thecentral portion of the diaphragm between the follower tit plate 428. Aregulating spring 522 contained in chamber 415 and supported at on endon the casing section 352 bears against the diaphragm follower lli;urging the diaphragm ill in the direction of cover M2.

The casing section a bore arranged in coaxial relation with thediaphragm til i and containing a plunger 52%. The plunger 323 isprovided on the end adjacentthe diaphragm lit with a stem 62% extendingthrough a chamber G25 and an axial bore in a bushing 52% secured in thecasing section 352, into chamber lit and thence through said chamberinto contact with the diaphragm follower 333. Adjacent to the followerH364 washer dill is secured to plunger through choke 394 and provide aforce on dia phragm 389 which will move same in the direction of chamber3% for thereby actuating the integral member its into seating engagementwith the valve 383 and for then shifting said valve against plunger3's"? to unseat the valve 336. Upon unseating of valve 3'55 the chamber361 at one side of the control piston 363 will be opened past said valveto passage 372 and thence to the outlet chamber 353 which may be open tothe direct bounce chambers in the gas generator (not shown). Thepressure in the supply piston chamber will thereby be reducedsufficiently below the supply pressure in chamber 239 to provide a forceon the piston to move same in a direction to pull the supply valve 355away from the seat whereupon fluid under pressure from the supply valvechamber 356 will flow to the outlet chamber and thence to the directbounce chambers in the gas generator.

As fluid under pressure is thus supplied to the direct bounce chambersin the gas generator (not shown) it will equalize through pipe 393 backinto diaphragm chamber 3% in the direct bounce governor device andthereby provide a force on diaphragm opposing pressure of fluid inchamber Elli. Since the area of diaphragm 385 subject to pressure offluid in chamber 3% is greater than that subject to pressure of fluid inchamber 39!, it will be seen that when the pressure in the formerchamber becomes increased to a degree somewhat less than that acting incharmber 39! said diaphragm will deflect in the direction of the lefthand to permit closing of valve Bit by spring 3%.

When the valve 31's in the direct bounce governor device is closed asjust described, fluid at the supply pressure in chambers 35 3, 356 atone side of piston 3&3 will promptly equalize through the passage Ettaand choke see into piston chamber whereupon spring 388d will actuatesaid piston to close the valve 355 for preventing further flow of fluidunder pressure to the outlet chamber and thereby to the direct bouncechambers in the gas generator and back to charm her 32- l Now let it beassumed that the tappet 22 is periodically operated to unseat the valve581, assuming the diaphragm ii A and valve seat did to be in theposition in which they are shown in the drawing. This periodic unseatingof valve 33'? will release fluid under pressure from chamber 395 tochamber which is at lower pressure. The venting capacity of valve it? isso in excess of the flow capacity or" choke to supply fluid underpressure to chamber 39! that the pressure in said chamber will becomereduced by the periodic unseating movements of valve 53! and hencepermit pressure of fluid in chamber 355 to deflect the diaphragm see inthe direction of the lower pressure in chamber 3% l such movementunseating the release valve to permit release of fluid under pressurefrom chamber 353 and the connected chamber When the pressure in thusbecomes reduced sufliciently pressure of in chamber its-i will deflectdiaphragm 55233 to close the release valve 383 for thereby limiting thepressure in chamber 3% to substantially the reduced degree acting inchamthe length of time which the valve :33? will be unseated for eachmovement of said tappet will be correspondingly greater resulting in acorresponding further reduction in pressure in chamber 39! and therebyoperation of diaphragm 38?;

to open the release valve 383 to cause a like reduction in pressure inchamber 391]. The pressure in chamber 390 will thus be reduced inaccordance with the increase in pressure in chamber M3, on diaphragm Alldue to the proportion" ally increased time which the valve as? is offits seat 436. On the other hand, if the pressure of fluid in chamber M3is reduced the seat 535 will be moved closer to valve 43! so that thelength of time which said valve will be oil its seat duringreciprocation of tappet 22 will be correspondingly reduced. As a resultthe pressure in chamber 39! will be increased by the supply throughchoke 3% relative to the pressure acting in chamber 39c and therebycause deflection of diaphragm 389 to open the supply pilot valve 318. Asbefore described, piston 363 will then open the supply valve 355 toincrease the pressure or fluid in chamber 358 and thereby in chamber seccorrespondingly, whereupon the diaphragm 388 will be deflected by fluidin the latter chamber to permit seating of the supply pilot valve 3'56and thereby closing of the supply valve to prevent further supply offluid under pressure to chamber 358.

If the length of stroke of tappet 22 is increased the same result willoccur as in case of increasing pressure of fluid in chamber 413, whileif the length of said stroke is shortened. the pressure in chamber 358will be increased the same as if pressure of fluid in chamber M3 isreduced.

It will therefore be seen that the fluid pressure regulating mechanism35c will operate to vary the pressure of fluid in chamber 353 inaccordance with operation of the control portion 3% or" the governor ascontrolled by pressure of fluid in chamber M3 and the length ofreciprocating stroke of tappet 22. As applied to a free piston gasgenerator where chambers 3.58 and see are open to the direct bouncechambers, chamber flit is open to the scavenger receiver for subjectingdiaphragm all! to pressure of fluid delivered by said generator, andtappet 2c is arranged. for reciprocation by the generator pistons nearthe end of their inward stroke, the direct bounce governor device willtherefore automatically vary the amount of fluid under pressure in thedirect bounce chamber of the generator as necessary to maintain adesired stroking of the generator pistons.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is:

l. A valve device for governing the quantity of fluid under pressure ina chamber comprising a casing, a supply valve cooperative with a seat insaid casing fo controlling supply of fluid under pressure to saidchamber, a release valve slidable in a bore in said casing in coaxialrelation to said supply valve, means connecting said valves for movementin unison, seating means for urging said supply valve to its seat, aflexible diaphragm in said casing arranged in coaxial relation to valvesand subject on one side to a variable control fluid pressure in acontrol chamber, follower means secured centrally to and movable withsaid diaphragm, seat means for said release valve movable with saidfollower means and disposed in said bore in sliding and sealing contactwith the wall thereof, said follower means having a a sess scavityva'and' a passage connecting said =cavity;to.-, said seat means,said release .valve;..controlling-.. communication betweenthe firstnamed chamber:- and said passage, conduit meansconnectingisaid cavitywith an atmospheric opening incsaidcasa ing, and means subjectingthe-opposite sidesof. said diaphragm to pressure of fluid from.thexfirsti named chamber whichopposes .pressureofzfluid's acting on saiddiaphragm in saidcontroli chamet ber; said diaphragm being operativeuponea pres. ponderance in pressure in .saidicontrol, chamber overthe-opposing pressure.:of'*fiuid-:to -seatasaid, release valve and opensaid supply valve and upon a preponderance in said opposing pressure offluid ,over; that. in said control chamber, to, ,rngve said seat means.outoi seating cooperation with said release valve and" topermit-seating of said supplyvallve by said seatingvmeans.

2". A valve deviceior governingithe quantity-oi fluidunder pressure-inchamb'eri comprisina; casing, a supply-valve cooperative-with ass-camsaid casing for controlling supply of fluid under. pressure to saidchamber, a1releasevalve slidable in aborein said casing in coaxialrelation to said supply valve, means connecting said valves for movementin unison, seating means for urging said Supply valve to its seat, aflexible diaphragm in said casing arranged in coaxial relation to saidvalves, follower means secured centrally to and movable with saiddiaphragm, seat means for said release valve movable with said followermeans and disposed in said bore in sliding and sealing contact with thewall thereof, said follower means having a cavity and a passageconnecting said cavity to said seat means, said release valvecontrolling communication between said chamber and said passage, conduitmeans extending through a fluid pressure control chamber at one side ofsaid diaphragm connecting said cavity to an atmospheric opening in saidcasing, means subjecting the opposite side of said diaphragm to pressureof fluid from the first named chamber which opposes pressure of fluidacting on said diaphragm in said control chamber, said diaphragm beingoperative upon a preponderance in pressure in said control chamber overthe opposing pressure of fluid to seat said release valve and open saidsupply valve and upon a preponderance in said opposing pressure of fluidover that in said control chamber to move said seat means out of seatingcooperation with said release valve and to permit seating of the supplyvalve by said seating means, choke means providing a constant controlledrate of supply of fluid under pressure to said control chamber, variableoperable means for releasing fluid under pressure from said controlchamber and automatically operative variable stroke means forcontrolling operation of said variable operable means to thereby varythe rate of release of fluidunder pressure from said control chamberwith respect to the constant rate of supply to thereby regulate pressureof fluid in said control chamber.

3. A valve device for governing the quantity of fluid under pressure ina chamber comprising a supply valve for supplying fluid under pressurefrom a source to said chamber, a piston connected to said valve andsubject on one side to pressure of fluid in said source and on theopposite side to pressure of control fluid in a control chamber, andoperative upon a reduction in the latter pressure to open said supplyvalve, a restricted passage connecting opposite sides of said piston forequalizing the fluid pressures on said opposite sides, spring means forclosing said supply valve 1 underrpressure; from: said chamber to,provide, a;

pressure therein corresponding to the length of 10 upon; equalizationof: fiuid apressures on: saidiopz positesides; aisupply pilot valvefor.releasingifluid under pressure from said control chambento the firstnamed chamber-,- a releaselvalve.arrangedin;

leasing fiuid-under pressure from: said first named; chamber, movable;abutment means subject to; fluidsunderpressure.from said-first namedchain: ber and: to an opposing; variable 1 control fluidpressureiin.a-seeond control chamber, andimeans operable-by said"; abutment. meansupon a DIE-.- ponderance: in. pressure in. said; second; control:chambenoyer the-opposing fluid pressure to close; said release valve andropen said-rsupplylpilot valve and-'upcna preponderance in:pressurerromsaid first: named chamberover that; in; said second;control ichambereto effect closing. of .;said supply; PiIQtiVEJVf-landiopeningl.ofi-saidirelease;valve;

4.: Ar. valve; device comprising means .provi.dingaiconstantaflowl,.-of.rfluid under; pressure to. a..con:-

'trol :chamber, aqfluid pressure release; passageway; OQHIIGGEGd-Tlldsaid chamber, coope ting. valve;

andivalverseat,elements controlling. communi tion.through;saidipassageway. for releasingfl time said elements are unseatedone from the other, pressure means responsive to variations of pressureof fluid for accordingly positioning one of said elements, andreciprocating means for intermittently unseating the other element fromsaid'one element.

5. A valve device comprising means providing a constant flow of fluidunder pressure to a chamber, cooperating valve and valve seat elementscontrolling a communication connected to said chamber for releasingfiuid under pressure from said chamber to provide a pressure thereincorresponding to the length of time said elements are unseated one fromthe other, a regulating spring, a movable abutment subject to pressureof said regulating spring and opposing pressure of fluid adjustable to aposition corresponding to the pressure of such fluid, means connectingone of said elements for adjustment by said abutment, and operatingmeans for intermittently moving the other valve element out of seatingcontact with said one valve element.

6. In combination, valve means for selectively supplying fluid underpressure to and releasing fluid under pressure from a chamber, movableabutment means controlled by opposing pressures of fluid in a firstchamber and in a second chamber which is adapted to be open to the firstnamed chamber, and operative upon a preponderance in pressure in saidfirst chamber over that in said second chamber to effect operation ofsaid valve 7 means to supply fluid under pressure to the first namedchamber and upon a preponderance in pressure in said second chamber overthat in said first chamber to erIect operation of aid valve means torelease fluid under pressure from the first named chamber, fluidpressure adjustable means and reciprocable means cooperable with saidfluid pressure adjustable means for controllingpressure of fluid in saidfirst chamber.

7. In combination, valve means for selectively supplying fluid underpressure to and releasing fluid under pressure from a chamber, movableabutment means controlled by opposing pressures of fluid in a firstchamber and in a second chamber which is adapted to be open to the firstnamed chamber, and operative upon a preponderance in pressure in saidfirst chamber over that in said second chamber to effect operation ofsaid valve means to supplyfiuid under pressure to the first namedchamber and upon a preponderance in pressure in said second chamber overthat in said first chamber to efiect operation of said valve means torelease fluid under pressure from the first named chamber, relativelymovable valve and valve seat elements cooperative to vary pressure offluid in said first chamber according to extent of movement of one ofsaid elements relative to the other, fluid pressure adjustable means forpositioning said other element in accordance with the pressure of suchfluid, and reciprocable means for periodically moving said one elementrelative to said other element.

8. In combination, valve means for selectively supplying fluid underpressure to and releasing fluid under pressure from a chamber, movableabutment means controlled by opposing pressures of fiuid in a firstchamber and in a second chamber which is adapted to be open to the firstnamed chamber, and operative upon a preponderance in pressure in saidfirst chamber over that in said second chamber to eiiect operation ofsaid valve means to supply fluid under pressure to the first namedchamber and upon a preponderance in pressure in said second chamber overthat in said first chamber to effect operation of said valve means torelease fluid under pressure from the first named chamber, relativelymovable valve and valve seat elements cooperative to vary pressure offluid in said first chamber according to extent of movement of one ofsaid elements relative to the other, fluid pressure adjustable means forpositioning said other element in accordance with the pressure of suchfluid, and variable stroke reciprocable means for periodically movingsaid one element relative to said other element.

ARTHUR J. BENT.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,047,581 Grissert July 14, 1936 2,376,671 Dodson May 22, 19452,401,680 Eaton June 4, 1946 2,411,748 Kelly Nov. 26, 1946 2,432,705,Williams Dec. 16, 1947 2,512,013 Down June 20, 1950

